Since time immemorial, Mexicans have argued that were it not for U.S. demand for illicit substances, Mexico would have a manageable drug problem. More recently, we have also contended that absent the U.S.'s laxity on arms sales and its tolerance for the possession of extraordinarily dangerous weapons, the violence in our country would not be what it has become. Lately our leaders have added a new gripe: Americans are hypocrites because they support prohibitionist and costly drug-enforcement policies  yet, through the specious fallacy of medical marijuana, are legalizing drugs without saying so.

Needless to say, these three points are absolutely valid, true, irrefutable ... and futile. They are the equivalent of believing that flowers and fruits would thrive in the desert if only it rained. They would, but it won't. Americans have not, and will not, reduce their overall consumption of drugs; they will not repeal the Second Amendment or reinstate the assault-weapons ban, which was introduced in 1994 and lapsed 10 years later; and the case against hypocrisy has always been overstated. (Read about Mexico's Deadly Knights Templar.)

When Barack Obama met Mexican President Felipe Calderón recently, he is said to have told him that U.S. drug consumption has dropped over the past 40 years and that the U.S. jails more people for drug-related offenses than any other wealthy country, by far.

Unfortunately, on the second point, Obama was right. The first point is more debatable. After Richard Nixon declared a war on drugs in 1971, U.S. consumption jumped through the late '70s and dropped slightly in the early '80s. Since the mid-'90s, overall demand has remained constant.

On weapons, there are two problems in addition to futile Mexican posturing. First, firepower is fungible. Even granting that most arms used in Mexico come from the U.S. (in fact, only the traceable ones do), there is no reason to suppose that if they stopped moving south, other sources and suppliers would not fill the void. Otherwise, the abundance of guns in countries from Brazil to Afghanistan would be inexplicable.

Most important, though, violence in Mexico did not increase when, in 2004, the assault-weapons ban expired and George W. Bush declined to resubmit it to Congress. (Obama hasn't either.) Willful homicide and every other form of crime had been diminishing in Mexico since the early 1990s and continued to do so until late 2007, precisely when Calderón's war on drugs went into high gear. As for medical marijuana, it is quite true that its use in most U.S. states amounts to legalization without admitting it. There is nothing wrong with this, although full-fledged legalization of marijuana production, commerce and consumption would be better. But if U.S. society feels more comfortable with the hypocritical regulation of pot and other drugs, so be it. What is the point of Mexicans' lecturing Americans about this, other than scoring debating points?
(See pictures of a Mexican drug gang's "holy war.")

In fact, the U.S. seems to be doing just fine with its current drug policies, cynical as they may be. Violent and property-related crimes are at their lowest levels in 40 years. The recession has not brought an increase in crime. So Mexico is not only barking up the wrong tree; mixing metaphors, it is also asking the U.S. to fix something that isn't broken. Perhaps another Mexican approach and a different U.S. policy might be more productive.

What would such an approach and policy entail? First, it would mean that instead of the U.S. pouring money into Mexico's military-based drug war, there would be far greater funding for the construction of a single national police force, as in Chile or Colombia, in contrast to the present broken system in which the police are under the control of state and municipal governments. Taken seriously, such a policy would include U.S. trainers and advisers in Mexico  a risky proposition but one that many polls suggest Mexicans would support. Next, the U.S. could give far greater assistance and technical help in building (finally  it has never existed) a functional justice system in Mexico, with oral trials, an independent prosecution structure and a federalization of the criminal code, a necessary corollary to a national police force.
(See the top 10 notorious Mexican drug lords.)

Finally, such a policy would include a far more receptive attitude in Washington to the case for legalization. Just weeks ago, the Global Commission on Drug Policy restated its views: the war on drugs has failed and cannot be won, and legalization should be seriously considered. Prominent Americans like Paul Volcker and George Shultz support that position; so do former U.N. Secretary-General Kofi Annan, together with ex-Presidents Fernando Henrique Cardoso, César Gaviria and Ernesto Zedillo, as well as Latin American celebrities like Mario Vargas Llosa and Carlos Fuentes. Wouldn't it be nice  as the Beach Boys once sang  if Obama paid attention to all of them, and to his predecessor Jimmy Carter, and looked at this option carefully instead of dismissing it out of hand?

Castañeda, a former Mexican Foreign Minister, is the author of Mañana Forever? Mexico and the Mexicans and teaches at New York University